Re: Narrow roads and vehicle choice...
What make/model/year C was it?
Was it Sprinter based or Ford/GM chassis based?
Not all class C RVs are width or height challenged.
They do have some nice features you won't get in a B. Usually loads of storage and usually a more conventional bathroom, with residential home type fixtures and amenities.
Since it sounds like you're got your itinerary pretty much pre-determined, maybe a small C, perhaps with a more agile toad, might be a better option for you. If you plan on traveling down skinny roads with height restrictions, you'll have to consider that when you make up your mind. Toads generally aren't bothered by terrain or road restrictions.
It's not a sprint(er) (unless you make it one), it's (hopefully) a marathon.
RV - 2018 Navion 24V + 2016 Wrangler JKU